Disconnecting switch



March 16, 1965 M. STENE ETAL DISCONNECTING SWITCH 2 Sheets-Sheet 1 FiledAug. 23, 1962 INVENTORS.

United States Patent 3,1743% DidiIQNNECTING SWITCH Manfred Stone and'(llarence H. Stumpfhaus, hicago, Ill., assignors to H. K. PorterCompany, Ind, Chicago, 1th, a corporation of Delaware Filed Aug. 23,1962, Ser. No. 219,013 8 Elatrns. (till. Edit-48) The present inventionrelates to disconnecting switches for high tension electrical powerinstallations, particularly to air break switches of the type having aswitch blade movable in an arc and rotatable about its own axis.

Air break switches of the character referred to are normally intendedfor outdoor installation, and in monthern climates are therefore subjectto icing conditions. Accordingly, it is essential that the switch becapable of freeing itself of ice and like obstructions if the switch isto be practical. One type of switch widely employed in the art ailords aparticularly efiicient solution to the problem by imparting to theswitch blade the characteristic movement of rotation within the switchcontact and arcuate movement toward and away from the contact to closeand open the switch. Assuming the switch to be closed, the same isopened by first imparting to the blade a predominantl rotary movementwithin the contact to shear any ice and free the blade end from thecontact, whereatter the blade is moved arcuately out of the contact toopen the switch. 011 closing of the switch, reverse operation occurs,i.e., the blade end is moved arcuately into the contact and then rotatedinto contact engagement. Because of this particular operation, theswitch further affords the distinct advantage of facilitating insertionof the blade end into and removal or" the blade end from the contactwith reduced contact pressure thereon, and yet allords an optimum highpressure small area engagement of the blade with the contact in switchclosed position. This is accomplished by flattening the blade end orforming the same of oblong or beaver tail configuration to cooperatewith a generally U-shaped contact having parallel legs or leaves. Thebeaver tall at the blade end has a minor dimension less than the spacingbetween the legs of the contact and a major dimension greater than thenormal spacing between the legs of the contact. The operating mechanismof the switch is so constructed md arranged that the blade end is movedinto the contact at least with the beaver tail inclined to the legs ofthe contact to accommodate insertion of the blade end into the contact.Subsequently, the operating mechanism rotates the blade to dispose themajor dimension of the beaver tail blade end transversely of the contactleaves or legs, thus to force the blade into high pressure small areaengagement with the contact. On switch opening movement, the operatingmechanism first rotates the blade to free the blade end from the highpressure engagement and thereafiter moves the blade arcuately out of thecontact.

In an early development of switches of this character, the operatingmeans or mechanism effected the above described rotary and arcuatemovements of the blade successively, but independently, so that bladerotation was effected entirely before removal of the blade end from thecontact, or entirely after entry of the blade end into the contact. Thisswitch afforded the advantages of high pressure, small area contact andice breaking on switch opening movement, but suiiered the particulardisadvantags that it was not fully controlled, i.e., on closing movementof the blade, if the contact were obstructed (such as by ice in anoutdoor installation), the switch blade could not be forced down throughthe obstruction by the operating means, but instead, the operating meanscould rotate the blade to complete blade movement even though the bladeend were not in the contact.

3,l74,0b4 Patented Mar, in, recs A further development in the art,disclosed in U.S. Patents 2,231,992 and 2,527,924, afforded bladecontrol in the region of the switch contact both in the opening andclosing directions. This switch is characterized by operating means foreffecting simultaneous rotation and arcuatc swinging of the blade, whichmeans comprises, in terms of a conventional horizontal switchinstallation, a frame defining a horizontal pivot axis, a blade guide orhinge pivotally mounted on the frame, a blade carriage to which theblade is secured rotatable in the blade guide or hinge about an axis atright angles to the horizontal pivot axis, an operating crank rotatableabout a vertical axis, and pivot means between the crank and bladecarriage, the pivot means in the specific embodiment being disposed withits axis at 45 degrees to the horizontal and vertical, and the operatingmeans being further characterized by intersection of the horizontalpivot axis of the blade guide or hinge, the axis of the blade, thevertical axis of rotation of the crank and the axis of the pivot meansin a common point. The switch as thus constructed affords particularadvantages over the earlier development in the art in terms of bladecontrol, for the operating means positively forces and drives the bladedownwardly into the contact on switch closing movement, and positivelyremoves the blade from the contact on switch opening movement. Therotary movement of the blade, while occurring simultaneously with thearcuate movement thereof, predominates in the region of the contact sothat the beaver tail blade end is readily inserted into and removed fromthe contact and is rotated an adequate extent within the contact toattain the previously described high pressure small area contact, andthe desired ice breaking functions at the switch contact both uponopening and closing movements of the switch blade.

Other switches predicated upon the same operational characteristics havebeen proposed, and substantially all have proven successful in use andhave been widely adopted.

However, two particular disadvantages have been occasioned with priorart switches; namely, (1) the tendency of the switch blade to be blownopen by momentary heavy current short circuit forces, and (2) failure ofthe blade to close under icing conditions and/ or to re-close afterbeing blown open by short circuit forces. Both of these disadvantagesmay in part be blamed on the flexibility of the switch blade, which inmost ratings is several feet long and inherently capable of flexure orbowing.

The object of the present invention, generally stated, is the provisionof improved switch means of the described character, and particularlyimproved switch means overcoming the stated disadvantages.

A first specific object of the invention is the provision of meanspreventing the switch blade from being blown out or" its stationarycontact and comprising a pair of latch members, one on the contact andone on the blade, which are brought into blade locking relation as theblade is rotated into high pressure engagement with the contact andwhich are released from one another during rotary movement of the bladeto release the high pressure con tact engagement, whereby the latchmembers do not interfere with opening or closing of the blade and yetare positively engaged and are not reliant on spring catches or thelike.

Another object of the invention is to provide means preventing theswitch blade from being blown out of its contact comprising latchmembers as above described which prevent outward movement of the bladeend, and a stop preventing excessive inward movement of the blade endand serving to confine the blade end between itself and said latchmeans.

A second specific object of the invention is to provide 3 improvedswitch blade operating mechanism for positively driving the blade endthrough ice on the stationary contact despite fiexure of the blade andto enhance the relationship between arcuatemovement and rotation of theblade, thereby to assure proper operation of the switch under allconditions.

An additional object of the invention is to provide improved switchblade operating mechanism maintaining full control over the blade, as inprior Patents 2,231,992 and 2,527,924, yet alfording even greater forcespositively driving the blade arcuately into the contact and thenrotating the blade through an even greater angle than henetofore.

A further object of the invention is the provision in switch means ofthe general character of the combination of the improved operatingmechanism and said latch means, whereby attainment of the latchingfunction isfacilitated by the increased angular rotation of the blade inthe contact.

Other objects and advantages of the invention will become apparent inthe following detailed description.

Now, in order to acquaint those skilled in the art with the manner ofmaking and using our improved disconnecting switch means, we shalldescribe, in connection with the accompanying drawings, a preferredembodiment of our switch means and the preferred manner of making andusing the same.

In the drawings:

FIGURE 1 is a side elevation of a disconnecting switch embodying ourinvention;

FIGURE 2 is a fragmentary side elevation, on an eni larged scale, of theimproved operating mechanism;

FIGURE 3 is an enlarged side elevation of the stationary contact and theend of the blade of the switch, and of the latch means of the invention;

FIGURE 4 is a cross-sectional view taken substantially on line 44 ofFIGURE 3 showing the switch in closed position;

FIGURE 5 is a fragmentary view similar to FIGURE 4 showing the blade endduring initial opening movement after about 30 degrees of bladerotation;

FIGURE 6 is a fragmentary view' similar to'FlGURES 4 and 5 showing theblade during opening movement after about 45 degrees of blade rotation;and

FIGURE 7 is a graph showing the relation between blade rotation andarcuate movement as imparted to the blade by the operating mechanism ofthe invention.

Referring now particularly to FIGURE 1 of the drawings, it will beobserved that the reference character Ill designates a channel iron basethat is mounted horizontally. It will be understood that the base ltlcan be mounted vertically and that it can be mounted in an invertedposition. For illustrative purposes, however, it is shown in ahorizontal position, but it can be mounted otherwise as stated.Accordingly, the words horizontal and vertical as used in thespecification and claims with respect to axes of certain elements of theswitch are to be considered .to express certain relative positions ofthe axes with respect to each other since, while the words accuratelyidentify the axes which are illustrated in the drawing, the vertica andhorizontal positions might change if the switch of this invention weremounted in other than a horizontal position.

The base 10 carries insulators Ill, 12 and 13 which are of conventionalconstruction and, as shown, may be of the pin type. The insulators 11and 13 at the ends of the base 10 are stationary. The intermediateinsulator 12 is rotatable. For this purpose a bearing 16 is mounted onthe base 10 and, as will appear hereinafter, constitutes the solebearing support for the insulator l2. Shank 17 projects below the base10 and is arranged to receive suitable crank means for rotating theinsulator 12. V

The insulator 11 at the upper end carries a terminal bracket 18 that maybe a bronze casting and it has a terminal pad 19 formed integrallytherewith to which a 4 terminal connector may be secured. Mounted on theterminal bracket 18 is a generally U-shaped stationary contact assembly21 of hard drawn copper or the like providing small area high pressurecontact engaging surfaces. Re enforcing springs 22 serve to urge thearms of the contactmembers 21 toward each other to provide the equiredcontact pressure.

At its upper end the insulator 13 carries a frame support 25 that may bea bronze casting and that has a terminal pad 26 for receiving a terminalconnector.

The frame support 25 carries a U-shaped contact assembly 28 which issimilar in construction to the contact 21 described above. The legs ofthe contact 28 are formed so as to provide the desired small areacontact engaging surfaces which are urged toward each other byreenforcing springs. The contact member 23 is secured to the framesupport 25 by bolts 3 The U-shaped contacts 21 and 28 are interconnectedin the switch closed position by a tubular switch blade 31 that may beformed of hard drawn copper. Its outer end is deformed, as shown inFIGURES 3 and 4, to define a beaver tail or oblong end portion 32 whichat its sides provides small area surfaces 33 that cooperate with thecorresponding contact surfaces of the legs of the contact 21.

At its other end, the switch blade 31 may be similarly deformed toprovide small area contact engaging surfaces for engaging thecorresponding surfaces of the contact 23.

The switch blade 31 is carried by a blade carriage which may be a bronzecasting suitably machined to shape. The carriage itiis rotatably mountedin a blade hinge 44 which, as shown in FIGURES 1 and 2, is mounted bybolts 45 on the frame support 25 to rotate about a horizontal axisthrough the longitudinal axis of the bolts 45. g

In order. to rotate the blade 31 about its longitudinal axis in theblade hinge 44 and also to swing the switch blade 31 to a verticalswitch open position, the blade carriage 40 is provided with an arm 46that extends angularly downwardly and rearwardly from the longitudinalaxis of the switch blade 31.

As illustrated more clearly in FIGURE 2, the arm 46 extends at an anglefrom the blade carriage 4t and is journalled in a bearing portion 48 ofa crank pin 49 that is secured to the rotatable insulator 12 and rotatesthererotated about its longitudinal axis to relieve the pressure betweenthe high pressure contact surfaces '35 and the stationary contact 21.Simultaneously, the rotation of the insulator 12 and of the crank pin 49causes the switch blade 31 to swing about the horizontal axis throughthe bolts 45. Reference herein to rotation of the switch blade about itslongitudinal axis to relieve pressure between it and a stationarycontact is intended to cover both of the following sequences of action:(1) where the pressure is relieved and a slight separation of thecontacts results from rotation of the switch blade about itslongitudinal axis, even before the blade is swung arcuately out of theneighborhood of the stationary contact, and (2) where most of thepressure is relieved between the contacts but separation results onlyduring arcuate movement of the blade out of the neighborhood of thestationary contact. It will be appreciated that our invention embracesboth types of separation and either one may be had by appropriateproportioning. Correspondingly, reference herein to swinging said switchblade out of engagement with the stationary contact is intended toembrace both of the following actions (related to actions 1 and 2 setforth above): (1) where the switch blade has already separated from thestationary contact by rotation of the switch blade about its ownlongitudinal axis, with the swinging movement thereafter carrying theswitch blade out of the neighborhood of the stationary contact toprovide a substantial air gap, and (2) where the blade has been rotatedto relieve most of the pressure between it and the stationary contactbut the two do not separate until the swinging movement has carried theblade out of the neighborhood of the stationary contact. When themovement of the insulator 12 has been completed the switch blade 31 ismoved to the full vertical open position and it has rotated about itslongitudinal axis.

The blade hinge 44 permits the switch blade 31 to rotate about itslongitudinal axis and is rockably mounted on the frame support 25 abouta horizontal axis through the longitudinal aXis of the bolts 45 onopposite sides. Movement of the blade hinge 44 guides the switch blade31 in its arcuate movement from the switch closed position shown inFIGURE 1 to a vertical switch open position and vice versa. Since theblade carriage 49 is fastened to the switch blade 31 and its arm 46 isrotatably mounted in the bearing portion 48 of the crank pin 49,rotation of the insulator 12 about its vertical axis causes the crankpin 49, which is secured thereto, to rotate about this vertical axis,and initially, the switch blade 31 to rotate principally about itslongitudinal axis and thereafter principally about the horizontal axisthrough the bolts 45.

When the insulator 12 is rotated in the reverse direction, the switchblade 31 is swung to the switch closed position. At the same time theswitch blade 31 is rotated about its longitudinal axis, its finalrotation about this axis taking place as it approaches the horizontalposition so that the final movement thereof into high pressureengagement with the contact 21 takes place while there is only a smallamount of arcuate movement. This permits the necessary torque to betransmitted through the switch blade 31 for rotating it into the switchclosed position with the contact surfaces under relatively highpressure.

The illustrated operating mechanism, to the extent thus far described,is very similar to the operating mechanisms of Patents 2,23l,92 and2,527,924. According to said patents, the blade operating arm 46 and thecrank bearing 48 are disposed at an angle of 45 degrees to both thevertical axis of rotation of the crank and the longitudinal axis of theblade. With this arrangement, blade rotation is equal, degree fordegree, with rotation of the crank 423 and arcuate swinging movement ofthe blade is essentially a trigonometric function of crank rotation.That is, as the crank is rotated from switch open or 90 degree positiontoward closed or zero position, arcuate movement of the blade isrelatively rapid and predominates over blade rotation so that the bladeis within about 3 degrees of its horizontal switch closed position afteronly 70 degrees of crank rotation, and thus 70 degrees of bladerotation. Thereafter, arcuate movement of the blade is substantiallyreduced and rotary movement of the blade predominates. Thus, the blademay be moved arcuately to nearly closed position with the beaver tail 32disposed in an inclined position so that it may enter the contact withrelatively slight frictional engagement with the contact leaves or legs,which pressure is continually increased as the blade moves further intothe contact. Finally, after about 85 degrees of crank rotation, theblade reaches horizontal position and maintains substantially thisposition during further rotation of the blade into position where thebeaver tail is disposed transversely between the contact legs. Since theblade has no significant arcuate movement during the last 5 degreesrotation of the crank, it follows that the blade would similarly have nosignificant arcuate movement during 5 degrees of over-travel of thecrank, i.e., 5 degrees beyond zero position to a total travel of 95degrees, thereby to accommodate 5 degrees additional twist of the blade.In this manner, full degrees of blade rotation can be accommodatedwithout any significant arcuate movement of the blade. At the same time,full control is gained over the blade as described in the introductoryportion of this specification.

In keeping with these operational characteristics, we have, as a primeobject of our invention, provided latch means for the switch, as bestshown in FIGURES 3 through 6. As shown, the latch means comprises agenerally L-shaped stationary member 59 secured to the terminal bracket18 of the stationary contact 21 and extending upwardly therefrom to aposition slightly below the horizontal switch closed position of theblade, to the side of the blade and immediately forwardly of the end ofthe blade in its closed position. At this location, the latch member 5%includes an inwardly projecting horizontal leg 51 disposed transverselyof the contact leaves or legs 21 and terminating a short distanceinwardly of the adjacent contact leg.

The switch blade 31 at its outer end is provided with a conventionalarcing horn 52 suitably in the form of a looped wire rod, the inner endsof which are anchored in the beaver tail end portion 32 whereby the hornis mounted for conjoint rotary and arcuate movement with the blade. Thewire rod at the side of the horn adjacent the member Sll is so formed asto define a downwardly extending loop or hook 53 which in the closedposition of the switch blade engages beneath the latch portion 51 of themember 5'1 In this position, as shown in FIG- URES 3 and 4, the latchmembers 51 and 53 positively prevent upward movement of the blade andthus positively prevent the blade from being blown upwardly out of itscontact by momentary heavy current short circuit forces.

When it is desired to open the switch, initial rotation of the crank 49will initially impart predominantly rotary movement to the blade 31 andthe arcing born 52. As shown in FIGURES 4 to 6, the latch member 53defined by the arcing horn is displaced a significant distance from theaxis of rotation of the blade and is also displaced from the contactengaging surfaces 33 in a direction transverse to the beaver tail oroblong end portion 32. Consequently, as the blade is rotated about itsaxis, substantial arcuate movement is imparted to the latch 53 wherebythe same is rotated, as shown in FIGURE 5, to a position wherein itclears the latch 51 before there is any significant arcuate movement ofthe blade Til. Thereafter, the

latch members 51 and 53 pose no obstacle to arcuate movement of theblade 31, so that the blade may be swung arcuately out of the contact inthe same manner as always.

As assistive means for the latching operation, we prefer to provide atransverse stop member 54 in the contact structure between the leaves orlegs thereof so as positively to define the horizontal closed positionof the switch blade. With the stop 54 in proper position, the blade,upon closing movement, will enter the contact at an inclination,somewhat as shown in FIGURE. 6, and be moved downwardly into the contactuntil the edge of the oblong end portion 32 adjacent the latch 51engages the stop 54. During this movement, the latch 53 is or" coursedisposed to one side of the latch 51 so that no obstacle is presented tofull entry of the blade end into the contact. Then, the blade will berotated about its axis to cause the latch 53 to be swung in under thelatch 51 (said latch being disposed substantially immediately above onlythe terminal portion of the arc of movement of the latch 53). Furtherrotary movement of the crank 49 will then cause the blade to rotatefully into the position where the oblong end portion 32 is disposedperpendicular to the legs of the contact leaves 21 and willsimultaneously impart a slight upward movement to the blade until thelatch 53 is brought into positive engagement with the latch 51,whereupon the two latch members positively prevent any further movementof the blade and its operating mechanism. In this position, the bladeend is positively locked against any significant degree of inadvertentmovement relative to the contact structure since the latches 51 and 53prevent the same from being blown upwardly out of the contact and thestop 54 prevents the blade end from being moved downwardly an excessivedegree into the contact. Thus, the blade effectively becomes lockedbetween the stop 54 and the latch means 51-53.

This positively locked blade feature will allow the momentary currentrating of a particular blade and contact combination to be increasedand, consequently, will permit a reduction in the number of contactsrequired in a multiple unit contact assembly for a given momentarycurrent rating. It therefore represents a substantial saving for theswitch manufacturer, as well as positive assurance for the user that theswitch blade cannot be blown open by mechanical forces caused by heavycurrent.

In addition the latch members 51 and 53 constitute a positive limit stopfor the closing operation of the blade, so that closed position stopspreviously provided in switches of the general character may now beeliminated. Specifically, the closed position stops 55 and 51 shown inFIGURE 10 of Patent 2,231,992 are no longer necessary, since the latchmembers of the present invention perform this function as one of theirattributes.

Further to enhance the operational characteristics of switches of thegeneral character, we provide as a second object of our inventionimproved operating mechanism for such switches. The present inventionparticularly utilizes the concept and attains all of the advantages ofthe operating mechanisms shown and described'in Patents 2,231,992 and2,527,924, and provides very substantial improvements therein,especially compensation for blade flexure, assurance of closing underall conditions and improved opening and closing performance, all by theapparently simple procedure of changing the relative angle of the arm 46and bearing 48. Specifically, by increasing the angular relationshipover the 45 degree angle previously dictated, the present inventionprovides for arcuate travel of the blade through a greater are ofmovement thereby compensating for blade flexure and assuring closingunder all conditions, and simultaneously provides a substantiallygreater period of arcuate quiesen-ce of the blade and a correspondinglygreater twisting of the blade within the contact thereby to enhanceopening and closing operations under all conditions. The variants of theangular relationship from. the prior art need only be a degree or two toachieve our new results.

Referring to FIGURES 2 and 7, we have illustrated 'herein a preferredembodiment of the improved operating mechanism of our invention. Asshown, the mechanism is the same as that of the above discussed priorart with the exception that the angles between the axis of the arm 46and bearing 48 and the axes of the blade 31 and the crank 49 have beenincreased to 4-6 degrees. By maintaining these two angles equal, theblade will have a vertical open position and blade rotation will bemaintained at a linear 1 to 1 ratio to crank rotation, as depicted bythe straight inclined line in FIGURE 7. However, by virtue of thischange the operating mechanism will. now impart 92 degrees of arcuateswing to the .blade (blade swing being equal to the sum of two changedangles) and the flattened end of the blade, following the curve depictedin FIGURE 7, will become disposed in blade closed or zero arcua-teposition after only about 75 degrees of movement in the closingdirection. Throughout the last degrees of crank rotation before reachingabsolute zero, the blade could dip 2 degrees below zero position asindicated by the dotted line in FIGURE 7. However, by virtue of the stop54- provided in the stationary contact assembly, the blade is caused tostop at zero horizontal position and to be maintained in said positionduring the continued rotation of the crank 49 and thus of the blade 31.Since there is substantially no lost motion in the operating mechanism,the structural 0 assembly results in considerable force being applied tothe blade such as actually to flex the blade as a normal part of itsclosing operation whereby extremely high pressure is applied to the endof the blade positively to drive the blade fully down into the contactand to break up any ice that may tend to bridge between the contactleaves or legs and/or accumulate on the position stop 54. In thismanner, blade closing force is greatly amplified over that heretoforeavailable and compensates effectively for the flexibility of the blade,thereby posi tively to insure complete, accurate closing of the bladeupon each operation.

As above stated, and as revealed by the graph of FIG- URE 7, theflattened or oblong end portion 3 2 of the switch blade completes itsarcuate swing after only about 75 degrees of movement in the closingdirection, and is then retained in zero arcuate position throughout thelast 15 degrees of crank rotation. Now, by providing 15 degrees ofovertravel (as contrasted to the prior art 5 degree of over-travel) topermit'the blade to return to a relaxed condition in zero arcuateposition, 30 degrees of crank rotation and thus 30 degrees of bladerotation is accommodated without any, or certainly no more than minimal,arcuate movement of the blade.

Referring to FIGURES 4 to 6, the blade is illustrated in fully closedposition in FIGURE 4. Upon blade opening rotation of the crank 4-9, theblade will initially and simultaneously start to rotate and todipslightly thereby to open a slight gap between the latch members 51 and53 to facilitate disengagement of the same. The blade end 32 at the edgethereof adjacent the latches will then engage the stop 54, whereafteronly rotary movement is imparted to the blade throughout an arc of 30degrees. At this point, as shown in FIGURE 5, the beaver tail or oblongend portion 32 of the blade is not only relieved of high pressureengagement with the contact leaves or legs 21 but'is actually completelyfree of said leaves. The blade will then simultaneously rotate andcommence its arcuate rise, until at degrees'crank rotationit will havecleared the contact structure substantially entirely,

' as revealed in FIGURE 6.

The greatly increased rotation of the blade end afforded according tothis invention results in four significant improvements in operatingperformance: (1) Since the blade is rotated through such a large angle,ice breaking'on switch opening and on switch closing is greatlyenhanced. (2) Since the blade is freed entirely from the contactstructure, there is no contact resistance to removal or insertion of theblade whereby energy is conserved and/or is rendered available for icebreaking functions, and the blade and contact are subject tosubstantially less wear'than heretofore. (3) Due to the increasedrotation, the flattened blade end or beaver tail may be made broaderthan heretofore without disadvantageous results, thereby to facilitateincreased contact pressures in the fully closed position of the switch.(4) The increased rotation enhances the operability and functioning ofthe latch means of this invention.

The above stated specific operational characteristics and advantagesare, as stated, attained by increasing the angles between the arm 46 andthe axis of the blade and between the arm 46 and the axis of the crank49 to 46 degrees. Further increase, and/or variable increase of theseangles will result in slightly varied operational characteristics whichmay be utilized for a variety of purposes. For the specific objectivesof the present invention, we prefer that the described angles bemaintained within the range of from about 46 degrees to about 48degrees. a

In view of the foregoing, it will be appreciated that the presentinvention provides substantial advantages in switches of the generalcharacter. Specifically, the latch means obviates the problem ofinadvertent switch opening under overload, permits use of simplified andmore economical contact structures and substitutes for position stopsheretofore required; the improved operating mechanism enhances switchoperation and renders the same positive and fully reliable bycompensating for blade fiexure, increasing the closing forces andaccommodating greater blade twist in the critical range of switchoperation; and the combination of these features provides a cooperative,complementary relationship resulting in a substantially improved switchstructure. Thus, the objects and advantages of the invention have beenshown herein to be attained in a convenient, economical and practicalmanner.

While we have shown and described what we regard to be the preferredembodiment of our invention, it will be appreciated that variouschanges, rearrangements and modifications may be made therein withoutdeparting from the scope of the invention, as defined by the appendedclaims.

We claim:

1. In a switch having a generally U-shaped stationary contact and aswitch blade arcuately swingable into and out of the contact to closeand open the switch, said blade having an oblong end portion enterableinto the contact and being rotatable in one direction upon closing ofthe switch to dispose said end portion transversely of the Contact andefifect high pressure engagement of said end portion with the legs ofthe contact and being rotatable in the opposite direction upon openingof the switch to dispose said end portion in a relatively inclinedposition and relieve said high pressure engagement prior to significantarcuate movement of the blade; the improvement comprising a first latchmember on the blade, said first latch member being displaced from theaxis of rotation of the blade and being displaced transversely downwardfrom the oblong blade end portion adjacent the edge thereof firstentering the contact upon closing movement of the blade, and a secondlatch member on said contact below the closed position of the blade andextending transversely of the legs of the contact in the directionopposed to the direction of rotation of said first latch member uponclosing movement of the blade, said second latch member including adownwardly facing latch surface disposed substantially immediately abovethe terminal portion only of the arc of rotation of the first latchmember upon rotation of the blade in its closing movement, said firstlatch member engaging the latch surface of said second latch member inits closed position and terminating closing movement of the blade, saidfirst latch member upon opening movement of the blade rotating clear ofsaid second latch member prior to significant arcuate movement of theblade.

2. In a switch having a generally U-shaped stationary r contact and aswitch blade arcuately swingable into and out of the contact to closeand open the switch, said blade having an oblong end portion enterableinto the contact and being rotatable in one direction upon closing ofthe switch to dispose said end portion transversely of the contact andeffect high pressure engagement of said end portion with the legs of thecontact and being rotatable in the opposite direction upon opening ofthe switch to dispose said end portion in a relatively inclined positionand relieve said high pressure engagement prior to significant arcuatemovement of the blade; the improvement comprising a first latch memberon the blade, said first latch member being displaced from the axis ofrotation of the blade and being displaced transversely downward from theoblong blade end portion adjacent the edge thereof first entering thecontact upon closing movement of the blade, a second latch member onsaid contact below the closed position of the blade and extendingtransversely or" the legs of the contact in the direction opposed to thedirection of rotation of said first latch member upon closing movementof the blade, and a stop in the contact preventing movement of theoblong end portion of the blade beyond switch closing position andretaining said end portion in such position whereby said blade is i9rotated through a substantial angle while the blade end portion isretained against arcuate movement, said second latch member including adownwardly facing latch surface disposed substantially immediately abovethe ter minal portion only of the arc of rotation of the first latchmember upon rotation of the blade in its closing movement, said firstlatch member engaging the latch surface of said second latch member inits closed position and terminating closing movement of the blade, theblade in its closed position being effectively locked in such positionby said stop and said latch members, said first latch member uponopening movement of the blade rotating clear of said second latch memberprior to significant arcuate movement of the blade.

3. In a disconnecting switch having a stationary generally U-shapedcontact and a switch blade with an end providing small area contactengaging surfaces, the blade being arcuately swingable from a verticalswitch open position to a horizontal switch closing position with saidend in the contact, the blade being rotatable about its axis in onedirection upon switch closing movement to dispose said end transverselyof the contact to move said surfaces into high pressure engagement withthe contact and being rotatable in the opposite direction upon switchopening movement to dispose said end in a relatively inclined positionto free it from the contact; operating mechanism for said platecomprising a stationary frame spaced horizontally from said contact, ablade hinge pivotally mounted on said frame on a horizontal axistransverse to the blade, a blade carriage fixed to said blade androtatably mounted on said hinge coaxially of the blade, an arm extendingangularly from said carriage, and a crank rotatably connected with saidarm and mounted for rotation about a vertical axis, the axes of theblade, the hinge, the arm and the crank intersecting substantially in acommon point and said arm extending at an angle of more than 45 degreesto both said vertical axis and the axis of the blade; said crank uponrotation through an angle in excess of 160 degrees rotating said bladethrough a substantially equal angle and imparting arcuate swingingmovement to said blade through an arc in excess of degrees wherein thearcuate swing imparted to the blade end adjacent horizontal switchclosing position is relatively insignificant during rotary movement ofthe blade through an angle in excess of 20 degrees; a first latch memberon the blade, said first latch member being displaced from the axis ofrotation of the blade and from the contact engaging surfaces thereof inthe direction generally of the plane of arcuate blade movement, and asecond latch member on said contact extending transversely thereof inthe direction opposed to the direction of rotation of said first latchmember upon closing movement of the blade, said second latch memherbeing disposed substantially immediately above the terminal portion onlyof the arc of rotation of the first latch member upon rotation of theblade in its closing movement to cause said first latch member to engagebeneath said second latch member on closing of the blade and to causesaid first latch member to rotate clear of said second latch memberprior to significant arcuate movement of the blade on opening of theblade.

4. In a disconnecting switch having a stationary generally U-shapedcontact and a switch blade with an oblong end portion providing smallarea contact engaging surfaces, the blade being arcuately swingable froma vertical switch open position to a horizontal switch closing positionwith said end in the contact, the blade being rotatable about its axisin one direction upon switch closing movement to dispose said oblong endportion transversely of the contact to move said surfaces into highpressure engagement with the contact and being rotatable in the oppositedirection upon switch opening movement to dispose said oblong endportion in a relatively inclined position to free it from the contact;operating mechanism for said blade comprising a stationary frame spacedhorizontally from said contact, a blade hinge pivotally mounted on saidframe on a horizontal axis transverse to the blade, a blade carriagefixed to said blade and rtatably mounted on said hinge coaxially of theblade, an arm extending angularly from said carriage, and a crankrotatably connected with said arm and mounted for rotation about avertical axis, the axes of the blade, the hinge, the arm and the crankintersecting substantially in a common point and said arm extending atan angle in the order of about 46 to 48 degrees to both said verticalaxis and the axis of the blade, said crank upon rotation through anangle in the order of about 105 degrees rotating said blade through asubstantially equal angle and imparting arcuate swinging movement tosaid blade through an arc in excess of 90 degrees wherein the arcuateswing imparted to the blade adjacent horizontal switch closing positionis relatively inconsequential during rotary movement of the bladethrough an angle of at least about degrees; a first latch member on theblade, said first latch member being displaced from the axis of rotationof the blade and being displaced transversely from the oblong endportion of the blade adjacent the contact engaging surface thereof firstentering the contact upon closing movement of the blade, and a secondlatch member on said contact extending transversely thereof in thedirection opposed to the direction of rotation of said first latchmember upon closing movement of the blade, said second latch memberbeing disposed substantially immediately above the terminal portion onlyof the arc of rotation of the first latch member upon rotation of theblade in its closing movement to cause said first latch member to engagebeneath said second latch member and terminate closing movement of theblade and to cause said first latch member to rotate clear of saidsecond latch member prior to significant arcuate movement of the bladeon opening of the blade.

5. In a disconnecting switch as set forth in claim 4, a stop in saidcontact preventing movement of said blade end beyond a substantiallyhorizontal position wherein said first latch member is maintainedadjacent said second latch member, said stop preventing arcuate movementof said oblong end portion of said blade beyond switch closing position,whereby said blade is rotated through a sub stantial angle while theblade end is retained against arcuate movement. a

6. In a disconnecting switch having a stationary generally U-shapedcontact and a switch blade with an end providing small area contactengaging surfaces, the blade being arcuately swingable from a verticalswitch open position to a horizontal switch closing position with saidend in the contact, the blade being rotatable about its axis to movesaid surfaces into and out of high pressure engagement with the contact;operating mechanism for said blade comprising a stationary frame spacedhori zontally from said contact, a blade hinge pivotally 5 mounted onsaid frame on a horizontal axis transverse E2 to the blade, 'a bladecarriage fixed to said blade and rotatably mounted on said hingecoaxially of the blade, an arm extending angularly from said carriage,and a crank rotatably connected with said arm and mounted for rotationabout a vertical axis, the axes of the blade, the hinge, the arm and thecrank intersecting substantially in a common point and said armextending at an angle of more than 45 degrees to both said vertical axisand the axis of the blade; said crank upon rotation through an angle inexcess of degrees rotating said blade through a substantially equalangle and imparting arcuate swinging movement to said blade through anarc in excess of 90 degrees wherein the arcuate swing imparted to theblade adjacent horizontal switch closing position is relativelyinconsequential during rotary movement of the blade through an angle inexcess of 20 degrees.

7. In a disconnecting switch having a stationary generally U-shapedcontact and a switch blade with an end providing small area contactengaging surfaces, the blade being arcuately swingable from a switchopen position to a horizontal switch closing position with said end inthe contact, the blade being rotatable about its axis to move saidsurfaces'into and out of high pressure engagement with the contact;operating mechanism for said blade comprising a stationary frame spacedhorizontally from said contact, a blade hinge pivotally mounted on saidframe on a horizontal axis transverse to the blade, a blade carriagefixed to said blade and rotatably mounted on said hinge coaxially of theblade, an arm extending angularly.

from said carriage, and a crank rotatably connected with said arm andmounted for rotation about a vertical axis, the axes of the blade, thehinge, the arm and the crank intersecting substantially in a commonpoint and said arm extending at an angle in the order of about 46 to 48degrees to both said vertical axis and the axis of the blade; said crankupon rotation through an angle in the order of about degrees rotatingsaid blade through a substantially equal angle and imparting arcuateswinging movement to said blade through an arc of at least about 92degrees wherein the arcuate swing imparted to the blade adjacenthorizontal switch closing position is relatively'inconsequential duringrotary movement of the blade through an angle of at least about 30degrees.

8. In a disconnecting switch as set forth in claim 7, a stop in saidcontact preventing movement of the oblong end portion of said bladebeyond horizontal position, said stop retaining said end portion of saidblade in switch closing position whereby said blade is rotated through asubstantial angle while the blade end is retained against arcuatemovement.

References Cited in the file of this patent UNITED STATES PATENTS

1. IN A SWITCH HAVING A GENERALLY U-SHAPED STATIONARY CONTACT AND ASWITCH BLADE ARCUATELY SWINGABLE INTO AND OUT OF THE CONTACT TO CLOSEAND OPEN THE SWITCH, SAID BLADE HAVING AN OBLONG END PORTION ENTERABLEINTO THE CONTACT AND BEING ROTATABLE IN ONE DIRECTION UPON CLOSING OFTHE SWITCH TO DISPOSE SAID END PORTION TRANSVERSELY OF THE CONTACT ANDEFFECT HIGH PRESSURE ENGAGEMENT OF SAID END PORTION WITH THE LEGS OF THECONTACT AND BEING ROTATABLE IN THE OPPOSITE DIRECTION UPON OPENING OFTHE SWITCH TO DISPOSE SAID END PORTION IN A RELATIVELY INCLINED POSITIONAND RELATIVE SAID HIGH PRESSURE ENGAGEMENT PRIOR TO SIGNIFICANT ARCUATEMOVEMENT OF THE BLADE; THE IMPROVEMENT COMPRISING A FIRST LATCH MEMBERON THE BLADE, SAID FIRST LATCH MEMBERS BEING DISPLACED FROM THE AXIS OFROTATION OF THE BLADE AND BEING DISPLACED TRANSVERSELY DOWNWARD FROM THEOBLONG BLADE END PORTION ADJACENT THE EDGE THEREOF FIRST ENTERING THECONTACT UPON CLOSING MOVEMENT OF THE BLADE, AND A SECOND LATCH MEMBER ONSAID CONTACT BELOW THE CLOSED POSITION OF THE BLADE AND EXTENDINGTRANSVERSELY OF THE LEGS OF THE CONTACT IN THE DIRECTION OPPOSED TO THEDIRECTION OF ROTATION OF SAID FIRST LATCH MEMBER UPON CLOSING POSITIONOF THE BLADE, SAID SECOND LATCH MEMBER INCLUDING A DOWNWARDLY FACINGLATCH SURFACE DISPOSED SUBSTANTIALLY IMMEDIATELY ABOVE THE TERMINALPORTION ONLY OF THE ARC OF ROTATION OF THE FIRST LATCH MEMBER UPONROTATION OF THE BLADE IN ITS CLOSING MOVEMENT, SAID FIRST LATCH MEMBERENGAGING THE LATCH SURFACE OF SAID SECOND LATCH MEMBER IN ITS CLOSEDPOSITION AND TERMINATING CLOSING MOVEMENT OF THE BLADE, SAID FIRST LATCHMEMBER UPON OPENING MOVEMENT OF THE BLADE ROTATING CLEAR OF SAID SECONDLATCH MEMBER PRIOR TO SIGNIFICANT ARCUATE MOVEMENT OF THE BLADE.